Winding for three-phase motors.



No. 785,995. PATENTED MAR.28,1905. E. P. W. ALEXANDERSON.

WINDING FOR THREE PHASE MOTGBS.

APPLIOATION FILED AUG.19, 1904.

Fiql.

i? li nstFiv/aqlexanderspn.

No. 785,995. Patented March.28, 1905..

UNITE STATEs' PATENT OEEIcE.

ERNST F. IV. ALEXANDERSON, OF SOHENEOTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEIV YORK.

WINDING FOR THREE-PHASE MOTORS.

SPECIFICATION forming part of Letters Patent No. 785,995, dated March28, 1905.

Application filed August 19, 1904. $eria1No, 221,321.

T (637/ 1077107 it y 007109770! switch adapted to vary its connectionsto pro- 50 Be it known that I, ERNST F. WV. ALEXAN- ducc two differentnumbers of poles. Fig. 2 DERsoN, a subject of the King of Sweden andshows a developmentof the winding on a plane Norway, residing atSchenectady, county of surface and arranged in accordance with my 5Schenectady, State of New York, have ininvention.

vented certain new and useful Improvements Although I have illustratedand shall de- 55 in Windings for'lhree-Phase Motors, of which scribe myinvention as applied to a two-speed the following is a specification.motor, since it is in a multispeed motor that Myinvention relates todrum-windings for the number of slots most frequently becomesthree-phase motors; and its object is to reduce excessive, neverthelessit will be understood the number of slots required for athree-phase thatmy invention is not limited to a multi- 6o winding of a given number ofpoles. speed motor, but is applicable to any three- In drum-windings asordinarily arranged phase machine in which it is desired to reduce inorder to produce evenly-spaced poles, while the total number of slotsbelow the product of at the same time permitting the use of formerthenumber of poles by the number of phases.

wound coils, it has heretofore been necessary Referring first to Fig. 2,the development 5 to have the total number of slots a multiple of awinding arranged in accordance with my of the number of poles and thenumber of invention is shown. One of the three phases phases. Vithathree-phase winding havinga only is shown in full lines, the othersbeing large number of poles the above arrangement indicated by dottedlines. It will be seen that necessitatesalarge number-of slots.Furtheradjacent coils of each phase are spaced from 7 more, when it isattempted to design such a each other by a distance equal to one-halfthe winding for more than one number of poles width of each coil, and itwill be seen that the total number of slots must be a multiple thisratio of coil Width to spacing renders it not only of the number ofphases, but also of possible for each slot to contain two coils of bothnumbers of poles. l/Vith high-potential different phases. It is thisfeature that ren- 75 machines the cost and difliculty of insulating dersit possible to employ a smaller number the armature-coils increases withthe number of slots than the product of the number of V of slots, sothat a three-phase winding for poles by the number of phases. 0 highpotentials and for a large number of I have shown the coils of eachphase conpoles becomes excessively expensive. nected in two groups,alternate coils being The object of my invention is to provide aconnected in the same group in order that the novel form of threephasedrum-winding direction of current may be reversed in alterwherebya totalnumber of slots maybe chosen nate coils, so as to vary the number ofpoles which is not divisible by the number of poles in the manner wellknown in the art. This and which may be smaller than the productconnection of the coils is indicated in Fig. 1, 5 of the number of polesmultiplied by the num- 'in which I have shown a three-phase Y conber ofphases. 1 accomplish this result by nected with each phase in twogroups. The forming each phase of the winding of coils of three phasesare connected, through a speed- 40 such a width with respect to thedistance be- -changjng switch D, to a source of three-phase tweenadjacent coils that each slot may concurrent 1 2 3. The speed-changingswitch D 9 tain two coils of different phases, thereby is shown ashaving two positions F and H, remaking it possible to use only one-halfthe spectively. The position F corresponds to usual number of slots.full speed of the motor, and when the switch l My invention will best beunderstood by is in this position the winding is connected for l I Ireference to the accompanying drawings, in its smallest number of poles,as will be herewhich inafter explained. Position H corresponds I Figurel shows diagrammatically a threeto half-speed, in which the winding isconphase winding provided with a controllingnected to produce twice thenumber of poles which it has when operating at full speed. arrangementshown;

Leads are brought from the terminals of the Y et 5 6 and also from theintermediate points 7, 8, and 9 to the controlling-switch.

The How of current in the windings may be traced as follows for the twopositions of the controlling switch: lVith the controllingswitch in theposition F the following circuits may be traced in Fig. 1: fromline-wire 3, contact-finger (Z, contact-finger (Z terminal 7, throughthe two portions of phase A in parallel to the neutral point 10, and toterminal 4, which is connected, through contactfingers CZ, (Z and d", toterminals 5 and 6. Similar circuits may be traced for the other phases,and consequently it will be seen that in this position of thecontrolling-switch the three phases are connected to form two Ys inparallel. Now by referring to Fig. 2 and tracing the direction ofcurrent-flow through the coils marked A it will be seen that poles areproduced, as indicated by the lines N S- that is, the motor is connectedfor four poles. It will be noticed that the width of each coil istwo-thirds the pole-pitch.

With the controlling-switch in the position H a circuit may be traced inFig. 1 from line wire 3 to contact-linger cZ', contact-finger (1,terminal 4, through all of phase A-to the neu tral point 10 of the Y.Similar circuits may be traced for the other two phases. Now referringto Fig. 2 it will be seen by tracing out the relative directions ofcurrent-flow in the coils marked A that for a given direction ofcurrent-flow poles will be produced by these coils, as indicated by theletters a .s that is, the winding produces eight poles. The width of acoil is four-thirds of the pole-pitch.

All eight-pole three-phase windings as hitherto constructed haverequired twenty-four slots as a minimum number. It will be seen that bymy invention I provide an eight-pole three-phase winding which may beplaced in twelve slots and which nevertheless is composed of formerwoundcoils. When the number of poles per phase becomes large, the insulationfor high-potential machines is an important factor in the design, andthe chiliculty of insulation is greatly reduced by my invention.

Although I have shown my invention as applied to a two-speed motor, itwill be understood that it is not limited to this particularapplication, but may be used with advantage for any three-phasedrum-winding for generators or motors of the synchronous ornonsynchronous type, in which it is desirable to reduce the number ofslots. Accordingly I do not desire to limit myself to the particular butin the appended claims I aim to cover all modifications which are withinthe scope of my invention.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-- 1. In an alternating-current dynamo-electricmachine, a three-phase winding composed of coils having a width equal totwice the distance between adjacent coils of the same phase.

2. In an alternating-current dynamo-electric machine, a three phasewinding each phase of which is composed of coils spaced by a distanceequal to one-half the coil width.

3. In an alternating-current dynamo-electric machine, a three-phasewinding disposed in slots, each slot containing conductors of twodifferent phases.

4.. In an alternating-current dynamo-electric machine, a three-phasewinding composed of coils each disposed in two slots each common toanother phase.

5. In an a lternating-current dynamo-electric machine, a three-phasewinding composed of coils having a width equal to twice the dis tancebetween adjacent coils of the same phase and each coil being disposed intwo slots each common to another phase.

6. In an alternating-current dynamo-electric machine, a three-phasewinding disposed in slots, each slot containing conductors of twodifferent phases and each phase being composed of coils spaced by adistance equal to one-half the coil width.

7. In an alternating-current dynamo-electric machine, a three-phasewinding composed of coils having a width equal to twice the dis tancebetween adjacent coils of the same phase, and means for varying theconnections of said winding to vary the number of its poles.

8. In an alternating-current dynamo-electric machine, a three-phasewinding composed of coils each disposed in two slots each common toanother phase, and means for varying the connections of said winding tovary the number of its poles.

9. In an alternating-current dynamo-electric machine, a three-phasewinding disposed in slots, each slot containing conductors of twodifferent phases and each phase having its alternate coils connected ingroups, and means for reversing the relative connections of said groups.

In witness whereof I have hereunto set my hand this 18th day of August,190%.

ERNST F. W. ALEXANDEHSON.

IVitnesses:

BENJAMIN B. IIULL, HELEN Onrom).

